Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 47: Correlated Electrons: Spin Systems and Itinerant Magnets 2
TT 47.12: Vortrag
Freitag, 30. März 2012, 12:30–12:45, H 0104
Vacancies in non-collinear antiferromagnets — •Alexander Wollny1, Lars Fritz2, and Matthias Vojta1 — 1Institut für theoretische Physik, Technische Universität Dresden, 01062 Dresden — 2Institut für theoretische Physik, Universität zu Köln, 50937 Köln
We study dilute magnetic impurities and vacancies in two-dimensional frustrated magnets with non-collinear order. Taking the triangular-lattice Heisenberg model as an example, we use quasiclassical methods to determine the impurity contributions to the magnetization and susceptibility. Most importantly, each impurity moment is not quantized, but receives non-universal screening corrections due to local relief of frustration. At finite temperatures, where bulk long-range order is absent, this implies an impurity-induced magnetic response of Curie form, with a prefactor corresponding to a fractional moment per impurity. We also discuss the behavior in an applied magnetic field, where we find a singular linear-response limit for overcompensated impurities.